Thread: MAF sensor
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      06-19-2013, 04:13 PM   #13
TDIwyse
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Drives: 2011 335d
Join Date: Aug 2012
Location: MidWest

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So, this week I started getting a P0101 MAF code. Only at higher engine loads. Using the Torque App I could quantify a ~10-15 hp loss compared to "normal" and lower peak boost readings (it uses the MAF readings to calculate boost). So... something strange was afoot.

Removed the MAF and noticed a small piece of cottonwood pollen clinging to the very middle section of the mesh screen on the air box side that protects the hot film element from debris. I replaced the air filter earlier this spring and perhaps that contaminant found its way in there during the process? Not sure. I removed that from the screen, and since it was already detached, decided to "clean" the sensor with CRC fluid. Sprayed it and the electrical connector, let dry, re-assembled.

Cleared code and road tested. No more codes at full fueling and the lost power was back.

Since I did two things at once I'm not sure which "fixed" the issue. Question for those with MAF experience: Could the pollen blockage directly in front of the hot film element cause enough turbulence/blockage to the air stream that the MAF reading at higher air utilization was out of whack? Or is it more likely that the CRC cleaning was the more likely cause for the improvement?
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